l. Field of the Invention
This invention relates to electrical filters, and particularly to a digital type filter.
2. General Description of the Prior Art
The removal of noise from communications signals, particularly those transmitted by radio where atmospheric noises are mixed with the signals, has long been a problem. Many types of filters have been devised to remove the noise. Usually they have been of the reactance type which function to block frequencies above and below the signal spectrum, approximately 300 to 3,000 Hertz in the case of voice signals. With the development of the digital computer, efforts have been made to solve the noise problem digitally by converting sampled values of a signal to digitally encoded bits and then performing, at very high speeds, various modifications to the encoded bits. The difficulty has been that the computer programs employed to accomplish this task have been too complex, too demanding of computer hardware, and too expensive.
It is the object of this invention to provide a new and improved means of filtering communications signals which substantially reduces the hardware requirement and yet enables extremely effective filtering.